Thermal shock occurs when a thermal gradient causes different parts of an object to expand by different amounts. This differential expansion can be understood in terms of stress or of strain, equivalently. At some point, this stress can exceed the strength of the material, causing a crack to form. If nothing stops this crack from propagating through the material, it will cause the object’s structure to fail.
Glassware in coffee brewing equipment is exposed to thermal shock when hot water, or coffee is poured into glass beakers, carafes, or other recipients. In order to solve the problem with glass cracking, manufacturers use borosilicate glass, which is resistant to thermal shocks.
For cold brew coffee preparation there is no need to use borosilicate glass, since the thermal shock is minimal, even with refrigerated steeping.